FPX Fire Uneven

[Snakebit12]

I also try to cut my wood to about 16-18", but the wide box does cause me to be a bit lazy. It is very convenient for taking odd and oversized logs near branch connections that I do not wish to take the time to properly cut to size.

Snakebit, I ordered the same thermometer. I will probably not get a chance to experiment with it until Thanksgiving week, but I will let you know what I find.

Isaiah, have you burned with the thermometer yet?

Here is what we are currently doing:

1. Start the fire with both doors slightly open - 1-1/2" maybe - cat disengaged, airslide to the far left and blower on low.
2. After 10-15 minutes, I close both doors.
3. The blower kicks in around 225°. I do nothing.
4. At 250°, I reduce the air about 40% - the right edge of the airslide is aligned with the right edge of the left-hand door.
5. At 300°:I engage the cat,and, after a few minutes, I move the blower to high.
6. I then reduce the air...for a day burn, I reduce the air another 10% or so by moving the airslide so it straddles the joint between the two doors, For a night burn, I reduce to probably 25% by aligning the left edge of the airslide with the left edge of the right-hand door. If the fire is really hot, I may push the airslide another 1/16" to the right but no more for fear of black glass.

My blower draws in outside air and we discovered that the house seemed a bit smokey when I had the blower on high while the cat was disengaged - visible smoke coming out of the chimney. We concluded that the blower was drawing smoke that exited the chimney. Once the cat is engaged, there is no visible smoke coming out of the chimney. Since we have adopted this technique, there has been no smokey smell in the house.

All in all, we are very pleased. Just experimenting to see if we can perfect our burning technique.

 

[Isaiah53]

Snakebit12,

Yes, I did receive and try out the thermometer. My experience has been similar to yours. Not sure I have a lot to add, but for what its worth:

1. I normally light off using small dead branches of fir and pine that I scrounge up. It burns really hot and gets the fireplace up to temperature quickly. I normally can close the doors as soon as it catches fire.

2. I placed the thermometer just above the right door handle like you recommended. The blower will consistently come on at about 200 F like yours. Typically takes about 20-30 minutes. I usually add 2-3 heavier splits or small logs as it is heating up to 200 F. I almost always run the blower on max for no reason other than my wife believes she overheated it one night with the blower on low (paint smell) and she is reluctant to turn it down. I have been engaging the cat and turning the air down to where the left edge of the slide bar is about even with the left side of the right hand door as soon as the blower comes on, but I may delay that now. I did not realize the firebox was this cool when the blower comes on.

3, I was generally operating between 300 and 400 F over the week. Below 275-300 F, I start getting black doors. Above 400 F, everything is very clean. The outside temperature was only in the low 40's during the day and the house was getting a little too warm (77-79 F) which limited my ability to experiment with higher temps. The unit does produce a monstrous amount of heat. I typically have just kept the air at that same low position and added wood when the temp drops below about 300 F. At this air setting the flames are reduced but still visible. Usually burns on one side of the box at a time, but will shift over when the wood is consumed.

4. One time when it was really cold outside, I drove the firebox up to over 500 F with max air and a roaring fire that filled the entire firebox, and then pushed the slide bar all the way to the right (minimum air). The flames went completely out and I was left with a bed of red logs and splits. The temperature dropped down to about 450-475 F and it held at that temperature for several hours, burning like a stove should. There was no creosote formation on the doors. I only had the firebox partially loaded, and my wood is soft and very light weight so I cannot really comment on what burn times you might get, but I was encouraged that I was able to turn the air flow down to minimum and go to coals without blackening the doors. Eventually, the temperature dropped down to about 300 F when the wood was largely consumed, at which point I increased the air for concern about blackening the doors. I intend to experiment with this more when it gets colder using a fuller loads. I think the key is getting the temperature very hot with a bed of coals before you turn down the air. Previously, I was trying this with the temperature below 400 F. I am interested to find out if the creosote will still form when the temp drops and there is very little wood at the end of the burn. I don't expect to get 12 hour burns times, but I am hopeful it will be extended.

To be honest, I was not expecting much from the thermometer, but it has actually been very useful in operating the fireplace - particularly with knowing when the box is getting too cold and is likely to start forming creosote.

 

[Snakebit12]

Snakebit12,

Yes, I did receive and try out the thermometer. My experience has been similar to yours. Not sure I have a lot to add, but for what its worth:

1. I normally light off using small dead branches of fir and pine that I scrounge up. It burns really hot and gets the fireplace up to temperature quickly. I normally can close the doors as soon as it catches fire.

2. I placed the thermometer just above the right door handle like you recommended. The blower will consistently come on at about 200 F like yours. Typically takes about 20-30 minutes. I usually add 2-3 heavier splits or small logs as it is heating up to 200 F. I almost always run the blower on max for no reason other than my wife believes she overheated it one night with the blower on low (paint smell) and she is reluctant to turn it down. I have been engaging the cat and turning the air down to where the left edge of the slide bar is about even with the left side of the right hand door as soon as the blower comes on, but I may delay that now. I did not realize the firebox was this cool when the blower comes on.

3, I was generally operating between 300 and 400 F over the week. Below 275-300 F, I start getting black doors. Above 400 F, everything is very clean. The outside temperature was only in the low 40's during the day and the house was getting a little too warm (77-79 F) which limited my ability to experiment with higher temps. The unit does produce a monstrous amount of heat. I typically have just kept the air at that same low position and added wood when the temp drops below about 300 F. At this air setting the flames are reduced but still visible. Usually burns on one side of the box at a time, but will shift over when the wood is consumed.

4. One time when it was really cold outside, I drove the firebox up to over 500 F with max air and a roaring fire that filled the entire firebox, and then pushed the slide bar all the way to the right (minimum air). The flames went completely out and I was left with a bed of red logs and splits. The temperature dropped down to about 450-475 F and it held at that temperature for several hours, burning like a stove should. There was no creosote formation on the doors. I only had the firebox partially loaded, and my wood is soft and very light weight so I cannot really comment on what burn times you might get, but I was encouraged that I was able to turn the air flow down to minimum and go to coals without blackening the doors. Eventually, the temperature dropped down to about 300 F when the wood was largely consumed, at which point I increased the air for concern about blackening the doors. I intend to experiment with this more when it gets colder using a fuller loads. I think the key is getting the temperature very hot with a bed of coals before you turn down the air. Previously, I was trying this with the temperature below 400 F. I am interested to find out if the creosote will still form when the temp drops and there is very little wood at the end of the burn. I don't expect to get 12 hour burns times, but I am hopeful it will be extended.

To be honest, I was not expecting much from the thermometer, but it has actually been very useful in operating the fireplace - particularly with knowing when the box is getting too cold and is likely to start forming creosote.

Good stuff. On your 4th bullet point, do you recall when you engaged the cat?

 

[jeffesonm]

You could try cutting some splits in half and then loading it N/S with the short splits just to see if you can jam more in there.

 

[BradleyW]

I am interested to find out if the creosote will still form when the temp drops and there is very little wood at the end of the burn

You shouldn't have too much to worry about at that point. Most of the gas has burned off by then.

 

[Isaiah53]

Good stuff. On your 4th bullet point, do you recall when you engaged the cat?

I don't recall at what point I engaged the cat, but it was probably 250-300 F. I think it was following a reload. I normally immediately engage the cat again after loading the wood if the fire is still present and the blower is still running. Again, I will probably change that practice in the future based on what I have learned from the thermometer. I usually open up the air fully after a reload to get the fire burning again. This time I was somehow distracted and let the fire burn at maximum air for quite a bit longer (maybe 30-40 minutes) and hence the 500+ temperatures. The cat was engaged during that entire time.

 

[weatherguy]

When you measure the wood with your moisture meter are you splitting the split in half and measuring in the middle of the freshly split wood?

 

[Richie]

I have the 44 as well and sometimes get a stronger fire on one side of the box but it is not the same side-it varies. I installed in 2005 and concur it put out serious heat. If I pack the box full north south I have gotten 10 hour burns with Black locust and black birch seasoned for three years. When I say 10 hours that means usable heat.

Last year I got a condor steel cat and there was quite a bit of play and the gasket did not expand as much as I thought. Now when I choke it down all the way I get smoke out of the chimney. That annoys the hell out of me. I do agree I get the best burns slightly right of the middle. The air controller bugs me in that is really hard to dial it in consistantly. I only damp it all the way down for overnight burns.

 

[Snakebit12]

When you measure the wood with your moisture meter are you splitting the split in half and measuring in the middle of the freshly split wood?

When I bring the firewood up to the house, I chop a few splits in half - from 16" splits to (2) 8" splits. I jam these shorties into the corners of the firebox. I check the moisture on the cut side of the shorties.

 

[Snakebit12]

I have the 44 as well and sometimes get a stronger fire on one side of the box but it is not the same side-it varies. I installed in 2005 and concur it put out serious heat. If I pack the box full north south I have gotten 10 hour burns with Black locust and black birch seasoned for three years. When I say 10 hours that means usable heat.

I started this thread with concerns about the stronger fire on the right side of the box. Now that I have a couple dozen burns under my belt, I too note that the stronger fire tends to switch sides. No apparent rhyme or reason. This probably means that my gasket is fine.

Just curious...how short do you cut the firewood for N/S loading?

 

[Richie]

I cut my wood about 14" and my can you load the firebox packed. I would guess I can get about 110 lbs of wood in there. I cut by eye and don't measure. The bulk of what I burn is loaded east west as I don't have a very good eye for cutting 14". The bulk of my wood is about 18" to 22". Longer wood has less of a likely hood to fall over stacked.